The present invention relates generally to loading software into a control panel. More specifically, the present invention relates to the loading of control software into the control panel of a liquid chiller system using a linear flash PCMCIA card.
The operation of a liquid chiller system can be controlled by a control software program(s) executed by a microprocessor on a control panel of the liquid chiller system. The microprocessor based control system typically includes a non-volatile memory device(s) or memory residing on a circuit board(s) in the control panel for storing the software program executed by the microprocessor during normal operation of the liquid chiller system. In microprocessor based control systems requiring only a small amount of memory for program storage, the non-volatile memory used in the control system typically resides in sockets on the circuit board, which socket configuration provides for easy insertion and removal of the memory. The non-volatile memory used for storing the smaller programs can include an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM), or a flash memory.
For microprocessor based control systems requiring a larger amount of memory for program storage, the control system typically has to use either several of the smaller, socket-based memory devices on the circuit board as described above, which usage of several memory devices may involve the occupation of a substantial portion of the circuit board, or a larger memory device (e.g., greater than 1 megabyte of storage capability) that is permanently installed, e.g., soldered, on the circuit board. The memory used for storing the larger programs can include a flash memory or, alternatively, a memory device that requires a separate controller, e.g., a hard disk drive or a compact flash card.
Many times during the operational life of the liquid chiller system, the control program executed by the microprocessor has to be updated or replaced. The updating of the control program can result in a new control program that provides more efficient operation of the liquid chiller system or that corrects errors that were present in the prior control program. To update a control program stored in a socket-based memory device, the old memory device storing the prior control program must be removed and a new memory device storing the new control program must be inserted. If several socket-based memory devices are used, the memory devices must be extracted and replaced in the correct order to ensure proper operation of the liquid chiller system. One drawback of this type of software update is that it can result in a substantial cost for the software update because of having to obtain new memory devices with the new control program.
To update a control program stored in a permanently installed memory device, the memory device must either be replaced with a new memory device through a difficult and time consuming process or provide for an electronic update of the memory device from a memory card or other medium. Typically, in an electronic update of the memory device, the memory card is an advanced technology attachment (ATA) or integrated drive electronics (IDE) configured flash memory card. To update a memory device using the ATA or IDE flash memory card, an intermediate controller has to read the information and control program stored on the flash memory card and then transfer the information and control program to the memory device on the circuit board for subsequent access by the microprocessor. One drawback of this technique is that the need for the intermediate controller increases the cost and the complexity of the control panel.
One technique for updating control software is provided in U.S. Pat. No. 6,330,806. In this technique, a flash miniature card having the control program for the system is installed or inserted into a card socket on the control panel and remains in the card socket during operation of a heating, ventilation and air conditioning (HVAC) system. The microprocessor reads the control program directly from the flash miniature card in order to control the HVAC system. A software update is completed by removing the current flash miniature card and inserting a new flash miniature card with the new control program. One disadvantage of this technique is that one card can be used to update only one system.
Another technique for updating control software is provided in U.S. Pat. No. 5,831,852. In this technique, a card is inserted into a card reader during operation of the system, which triggers a pulse generator to generate a signal for a microprocessor. In response to this signal from the pulse generator, the microprocessor identifies the first addressable storage location in memory for the control software, which can be in a higher ordered addressable memory bank or in a lowered order addressable memory bank. Selection logic uses signals from the microprocessor (highest ordered address bit) and from the card reader to determine whether to address the memory bank which is to store the control software or to address the card. The copying of the program is completed by executing a copy program stored on the card, which provides for the microprocessor to receive the information from the card and transmit the information to the appropriate memory bank. One disadvantage of this invention is that involves complicated circuitry to determine where to store the control software and when to initiate the copying process.
Therefore, what is needed is an economical control panel configuration that can provide for the quick, easy and repeated loading and updating of control software into the control panel of a liquid chiller system.